This invention relates generally to surgically implantable valves. More particularly, the present invention relates to one-way flow control valves for controlling the flow of cerebrospinal fluid out of a brain ventricle and preventing backflow of fluid into the brain ventricle.
As is well known in the medical arts, to relieve an undesirable accumulation of fluids it is frequently necessary to provide a means for draining a fluid from one part of the human body to another in a controlled manner. This is required, for example, in the treatment of hydrocephalus, an ailment usually afflicting infants or children in which fluids which ought to drain away accumulate within the skull and thereby exert extreme pressure and skull deforming forces.
In treating hydrocephalus, cerebrospinal fluid accumulated in the brain ventricles is drained away by a catheter inserted into the ventricle through the skull, and the catheter is connected to a tube which conducts the fluid away from the brain to be reintroduced into the vascular system, as by extending through the patient's jugular vein to the atrium portion of the heart, or the peritoneal system. To control the flow of cerebrospinal fluid and maintain the proper pressure in the brain ventricle, a pump or valve is placed in the conduit between the brain and the heart atrium or the peritoneum.
Many such devices have been used in the past, but some prior devices have tended to become obstructed by particulate matter entering the drainage system or by backward diffusion of blood into the system. Further, some prior devices have included moving parts which tended to adhere to other parts of the device and become immobile. When this occurs, the device itself becomes a barrier in the drainage system and it adds to the problem it is intended to solve.
U.S. Pat. Nos. 4,560,375 and 4,636,194 illustrate cerebrospinal fluid flow control valves which overcame many of the drawbacks of the prior art and which have realized great success in the marketplace. However, particularly with prior burr-hole valves, a problem was encountered when surgeons would insert needles into a fluid reservoir to either sample fluid therein or to inject a medication distally. If the needle happened to puncture the fragile flow control membrane, it would be left with an aperture thus destroying the utility of the valve. To counter this, manufacturers have been providing needle guards over the flow control member.
Although such flow control devices are intended to limit the flow of fluid in one direction only, i.e., from a proximal inlet port in fluid communication with the brain ventricle to a distal outlet port in fluid communication with the discharge catheter, it is desirable at times to provide proximal access through the flow control device to the brain ventricle. Prior valve designs which accommodate such proximal access have been less than optimal because they either expose the flow control membrane to unwanted damage by a needle, or more complicated valve designs are required which move the flow control membrane from adjacent the inlet and substitute a septum/flapper component in order to maintain the distal flushing capability of the flow control device.
Accordingly, there has been a long existing need in the medical arts for a convenient and effective device for controlling the flow of fluid from one part of the human body to another, which device is relatively inexpensive to manufacture and which can be constructed of substantially non-metallic parts which are not subject to adhering to one another and causing a malfunction of the device. Additionally, such a device is needed which provides repeated proximal access therethrough without changing the flow control characteristics of the device. As will become apparent from the following description, the present invention satisfies these needs and provides other related advantages.